Automatic fluid replenisher for hydraulic feed device

ABSTRACT

Fluid in the control cylinder of a hydraulic feed device is replenished as needed by a filler assembly in communication with the cylinder. The filler assembly includes a fluid containing reservoir and a spring loaded bolt having an &#39;&#39;&#39;&#39;O&#39;&#39;&#39;&#39;-ring seal at the dispensing end thereof. Air trapped within the cylinder is able to escape through the seal while fluid in the reservoir can enter to replenish the supply within the cylinder.

United States Patent [72] lnventor Charles A. OConnor East Norwich, N.Y.

[21] AppLNo. 819,172

{22] Filed Apr. 25,1969

[45] Patented June 8, 1971 [73] Assignee Richard J. Maehr Dix Hills, N.Y.

A part interest [54] AUTOMATIC FLUID REPLENISHER FOR HYDRAULIC FEED DEVICE 4 Claims, 4 Drawing Figs.

[52] U.S.Cl 137/199, 137/513.5 [51] Int. Cl F15b1/06 [50] Field of Search 137/199,

Primary Examiner-Allan Cohan Attorney-Albert F. Kronman 60/54.6UX 137/541X 60/54.6UX 60/54.6 137/199X 137/541 60/54.6

ABSTRACT: Fluid in the control cylinder of a hydraulic feed device is replenished as needed by a filler assembly in communication with the cylinder. The filler assembly includes a fluid containing reservoir and a spring loaded bolt having an O- ring seal at the dispensing end thereof. Air trapped within the cylinder is able to escape through the seal while fluid in the reservoil'. can enter to replenish the supply within the cylinder.

PATENTED JUN 8 |97| AUTOMATIC FLUID REPLENISHER FOR HYDRAULIC FEED DEVICE BACKGROUND OF THE INVENTION Actuation of the tool holding spindle on drill presses, vertical boring mills and the like is frequently accomplished by pneumatic means. However, strictly pneumatic actuators have a downward momentum buildup in the spindle before the tool contacts the work. Doe to this buildup the tool often breaks when it hits the work. After the tool reaches the surface of the work there is a pause while the air in the pneumatic cylinder is compressed enough to drive the tool into the work. During this interval the work particularly in such materials as stainless steel and the like may become work hardened beneath the spinning tool so that the tool may not thereafter be able to cut into the work. It has been found that the addition of a hydraulic section to the feed device eliminates the shortcomings of the pneumatic system. However, it is essential that the fluid in the hydraulic cylinders remain at the necessary levels at all times. The present invention fulfills the requirements of a satisfactory tool feeding device.

SUMMARY OF THE INVENTION In one embodiment of the present invention motion is imparted to the spindle of a vertical boring mill by means of a rack and pinion assembly. Motion is imparted to the rack by a rod slidably received within a two-chambered cylinder. A piston is carried in each of the chambers and secured to the rod. One of said pistons is driven by air admitted into the cylinder in which it slides. Fluid in the other cylinder controls the motion of the rod by means of valves and fluid lines. A fluid replenishing reservoir in communication with the fluid bearing cylinder permits air therein to escape to the atmosphere and fluid from the reservoir to enter the cylinder.

DESCRIPTION OF THE DRAWINGS In the accompanying drawing forming part hereof there is illustrated one complete embodiment of the present invention in which drawing similar parts have been given the same reference numbers and in which:

FIG. 1 is a view in front elevation of a complete embodiment ofthe present invention.

FIG. 2 is a view in longitudinal section taken on line 2-2 in FIG. 1 with certain elements indicated diagrammatically.

FIG. 3 is a fragmentary view in longitudinal section ofa portion of the spindle actuating mechanism somewhat enlarged.

FIG. 4 is a cross-sectional view of the oil filling device on an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing and particularly FIG. 1, indicates the head ofa vertical boring mill or the like. A spindle 11 is rotatably carried by the head 10 and is driven by a source of rotary power (not shown). Vertical motion is imparted to the spindle 11 by means ofa rack and pinion arrangement 12 mounted within the boring mill head 10. The drive shaft for the rack and pinion arrangement 12 extends outwardly of the head 10 as indicated at 13 and has a spur gear 14 secured to the outer end thereof. The spur gear 14 is in turn driven by a gear rack 15, best shown in FIG. 2. It will be apparent that as the gear rack 15 is advanced or withdrawn the spindle 11 will be raised or lowered in the milling machine head 10.

The gear rack 15 is reciprocated by means of an actuator 16. The actuator 16 is built within an elongated cylindrical housing 17 having an end wall 18 at one end thereof and a second end wall 19 at the opposite end. A partition 20 between the end walls 18 and I9 divides the housing 17 into two cylindrical chambers. The partition 20 is centrally bored as indicated at 21 to receive an actuating rod 22 therethrough.

The rod 22 has a piston 23 secured to one end thereof and a second piston 24, which may be integral with the rod 22 disposed within the chamber between the end wall 18 and the partition 20. The pistons 23, 24, may be provided with sealing O-ring 25, 26, and another O"-ring 27 is carried by the partition 20 around the rod 22. The forward end ofthe actuating rod 22 is threadably secured to the gear rack 15 as shown at 28.

An oil filler reservoir 29 best shown in FIG. 4, is carried by the end wall 18 and is preferably made of plastic or some transparent material so that the liquid level therein may be observed. The reservoir 29 is connected to the highest point of the cylindrical housing 16 to assure complete air removal in the manner hereinafter more fully set forth.

The reservoir 29 is provided with a fitting 30, which is threaded into a bore 31 in the end wall 18. The bore 31 is in communication with the interior of the cylinder 32, (hereinafter referred to as the front cylinder). Oil from the reservoir 29 is therefore able to flow into the front cylinder 32.

A second bore 33 is provided in the end wall 18 to receive hydraulic fluid coming from the line 34. The hydraulic line 34 interconnects the volume of the front cylinder 32 on each side of the piston 24. The partition 20 is bored as indicated at 35 to receive the opposite end of the fluid line 34 and communicate with the interior of the front cylinder 32. A second partition bore 36 is provided to receive an air conduit 37 and permit air to enter and leave the rear cylinder 38. Air may also be led into the rear cylinder 38 on the opposite side of the piston 23 by means of the line 39 and bore 40 provided in the end wall 19.

It will be apparent that the actuator 15 is a combined pneumatic-hydraulic system. The front cylinder 32 is filled with a suitable hydraulic fluid, such as oil, and the rear cylinder 38 is controlled by air entering and leaving the lines 37, 39. The advantages of such a system over a purely pneumatic actuator are that the downward momentum buildup in the spindle 11 before the drill contacts the work, which can cause tool breakage when the drill hits the workpiece can be effectively controlled. In addition, a positive and uniform feed rate can be maintained whereas in the pneumatic actuator the cutting tool tends to stop at the surface of the work until such time as sufficient pressure builds up to force it into the material. During this stopping period the metal becomes hardened due to the polishing action of the drill or cutting tool as a result ofwhich the tool may not cut when the pressure builds up.

With the front cylinder 32 filled with a relatively incompressible fluid, such as mineral oil, and a metering valve 41 placed within the fluid line 34, the forward motion of the piston 24 can be regulated and made constant. The valve 41 is preferably a pressure compensated flow control valve, which will assume constant flow through the valve regardless of the differential pressure across the valve. Valves of this type are provided with an adjusting valve 42 by means of which the flow can be set.

When the line 39 has air pressure applied thereto, the piston 23 will be forced in the direction of the gear rack 15 causing the rod 22 and piston 24 to move with it. Oil in the forward section of the front cylinder 32 will be forced to flow through the bore 33, the fluid line 34, through the flow control valve 41, which meters the oil at a uniform rate, and back into the cylinder 32 on the opposite side of the piston 24 by way of the bore 35. After the drilling tool has been advanced by the spindle II a desired amount, the pneumatic line 39 is exhausted through the atmosphere and air pressure applied to the line 37 to retract the piston 23 and consequently the gear rack 15 in a rapid manner. During the rapid retraction, an electric solenoid valve 43 is caused to open by the control mechanism for this system (not shown), thereby bypassing oil past the flow control valve 41 as returning it to the front cylinder 32 on the gear rack side of the piston 24. The unrestricted connection of the bores 33, 35, permits rapid retraction of the tool bit.

Any air trapped in the forward section of the front cylinder 32, due to its compressible nature, could cause the system to function as though it were a purely pneumatic system. Since it is undesirable to have a purely pneumatic system, an automatic oil filter and air eliminator 44, which includes the reservoir 29 and the fitting 31 is provided.

lt will be seen from an examination of FIG. 4 that a rod 45 extends through the oil reservoir 29 and down into the bore 3!, traversing the fitting 30. A small collar 46 is secured to the upper end of the rod 45 and a coil spring 47 is interposed between the collar 46 and the bottom 48 of the reservoir 29. The coil spring urges the rod 40 toward the top of the reservoir 29 at all times. The rod 45 may be made of an elongated bolt having a head 48 at the end thereof. The head is of a diameter larger than the bore 49 in the fitting 30 through which the rod slides. An "O-ring 50 is carried by the rod 45 between the head 48 and the bottom of the fitting 30. The top of the reservoir 29 is provided with a small cap 51 having a hole 52 therein to permit air to escapefrom the reservoir 29.

The operation of the automatic oil filler and air eliminator 44 is as follows: the loading of the spring 47 is adjusted by means of the threaded collar 46 so that when the head 48 of the rod 45 is in the position shown in solid lines in FIG. 4, a gastight seal is not provided due to the normal surface roughness of the bottom of the fitting 30. During that part of the cycle when the drill is being retracted, air can flow past the seal up through the bore 49 and out of the hole 52in the reservoir 29. As air leaves the reservoir 29 oil flows into the cylinder 32 through the bore 31. As pneumatic pressure is applied to the piston 23, pressure within the front cylinder 32 builds up forcing the head of the rod 45 against the ring 50 thereby effectively sealing the bore 49. If during the retraction of the drive rod 22 a vacuum is caused in the front cylinder 32, due to compression of the trapped air in the cylinder 32 on the opposite side of the piston 24, the head 48 of the rod 45 will be pulled downwardly as indicated in dashed lines in FIG. 4 thereby permitting oil to flow into the cylinder 32 to keep it filled at all times. It will be apparent that the device not only adds oil to the cylinder in the manner described, but makes up for any losses through cylinder or line leakage.

Having thus fully described the invention, what I claim as new and desired to be secured by Letters Patents ofthe United States, is:

I. An automatic fluid replenisher for connection to a fluid bearing cylinder having a reciprocating piston therein comprising, a fluid retaining reservoir having a fluid receiving opening at the upper end thereof, a base on said reservoir, a longitudinally bored fitting received at one end in said base and extending downwardly of said base, said fitting bore being in communication with the interior of said reservoir, a spring loaded rod slideably carried within the fitting bore, an enlarged head member on said rod overlying the bottom of the fitting, a compressible ring between the rod head member and the bottom of the fitting, said ring being in nonsealing contact with the fitting in the absence of pressure within the cylinder whereby the fluid in the reservoir is substantially prevented from leaving the reservoir when the head member is resting on said ring and means to secure the'bottom of the fitting to the cylinder with the fitting bore in communication with the interior of said cylinder.

2. A device according to claim 1 in which the rod extends upwardly into the reservoir and the spring loading is provided by a collar on said rod and a spring member disposed between the collar and the reservoir base.

3. A device according to claim 2 in which the collar is threaded upon the rod and adjusted to give the spring sufficient tension to hold the head member against the seal when the pressure within the cylinder exceeds ambient pressure.

4. A device according to claim 2 in which the ring is an 0"- ring and the fluid receiving opening in the reservoir is covered by a perforate cap. 

1. An automatic fluid replenisher for connection to a fluid bearing cylinder having a reciprocating piston therein comprising, a fluid retaining reservoir having a fluid receiving opening at the upper end thereof, a base on said reservoir, a longitudinally bored fitting received at one end in said base and extending downwardly of said base, said fitting bore being in communication with the inTerior of said reservoir, a spring loaded rod slideably carried within the fitting bore, an enlarged head member on said rod overlying the bottom of the fitting, a compressible ring between the rod head member and the bottom of the fitting, said ring being in nonsealing contact with the fitting in the absence of pressure within the cylinder whereby the fluid in the reservoir is substantially prevented from leaving the reservoir when the head member is resting on said ring and means to secure the bottom of the fitting to the cylinder with the fitting bore in communication with the interior of said cylinder.
 2. A device according to claim 1 in which the rod extends upwardly into the reservoir and the spring loading is provided by a collar on said rod and a spring member disposed between the collar and the reservoir base.
 3. A device according to claim 2 in which the collar is threaded upon the rod and adjusted to give the spring sufficient tension to hold the head member against the seal when the pressure within the cylinder exceeds ambient pressure.
 4. A device according to claim 2 in which the ring is an ''''O''''-ring and the fluid receiving opening in the reservoir is covered by a perforate cap. 